LPG Vapor Injectors

[gasresearch]

Could someone please advise where it is possible to purchase quality vapor injectors for propane/lpg at a reasonable cost. Particularly injectors that will supply large capacity engines.

Thanks guys.

 

[turbocohen]

http://www.vialle.nl/

Head on over to Eindhoven Netherlands. They can deliver lp any way you want. 20 liter engines no problem.
Here in North America contact Teleflex GFI handles vapor.


There are others out there but frankly damn near all of them are unable to handle large displacement.

 

[CNGBrick]

http://www.afsglobal.com

Large capacity injectors for LPG/CNG/H2

 

[turbocohen]

Re the AFS injector, should I assume it is a choked flow type? The web site says flow rate will change with down stream back pressure.

 

[CNGBrick]

What do you mean by "choked flow type"? As far as I know, solenoid-type fuel injectors have a fixed open flow area and thus are affected by upstream and downstream pressures in the same way as any other restriction in a gas stream.

In general, the ratio of upstream to downstream pressure determines if the flow at the restriction is in sonic flow condition or below sonic flow condition. When the flow is "sonic" the main determinant of flow is the upstream pressure only. When the flow is below "sonic" both the upstream and downstream pressures affect the flow through the restriction.

The pressure in a vehicle LPG system is generally kept low (with respect to a CNG or H2 system) to ensure the fuel remains gaseous under operating conditions. The result is that the pressure differential at the fuel injector may be insufficient to maintain "sonic" flow conditions. This is a generalization and applies to any gaseous fuel injector as far as I know.

In the case of pure propane (the main constituent of LPG), the upstream absolute pressure must be greater than 1.73 times the downstream absolute pressure of the restriction to maintain "sonic" flow conditions. We have to keep in mind that LPG composition varies in different geographic locations and may include a significant proportion of butane which will further lower the useful allowable operating pressure.

Hope this helps.

 

[turbocohen]

Choked flow aka sonic across a metering orifice or "choked area" such as needle to seat lift area. Thanks for clarifying this for the forum.

All my work with h2 or ng was sonic.. 5 bar absolute minimum or higher was the spec required to accomodate sonic flow on most boosted engines. There has been interest in larger injectors for H2 use but generally an injecotor with greater than a choked flow flow rate comparable to a 3.3mm orifice will require a lot of power to drive and as inlet pressures drop the opening and closing times become erratic, influenced by manifold pressure variables, etc.

In the case of low pressure LPG metering, as butane fraction increases in moderately cool weather of even straight propane in alaskan weather, then solenoid gaseous metering accuracy is toast due to environmental factors and that is why liquid metering may be a better choice for larger engines. -40F cold start using pure butane or propane is not a problem with liquid, vapor systems we competed with either barely started or flashed the game over light.